Creep feed intake during lactation enhances net absorption in the small intestine after weaning

The aim of the study was to measure the effect of creep feeding during lactation on net absorption in the small intestine at 4 days after weaning. Intermittent suckling was used to increase creep feed intake during lactation. Creep feed containing chromic oxide was provided. Based on the colour of the faeces, piglets were classified as ‘eaters’ or ‘non-eaters’, respectively. At day 4 after weaning, an in vivo small intestine segment perfusion test was performed at 5 sites along the small intestine in 24 piglets (12 eaters and 12 non-eaters). At both sides of each intestinal segment a tube was fitted to perfuse and drain fluid in order to assess net absorption. Net absorption was higher in eaters than in non-eaters (P < 0.001). Net absorption varied greatly between and within piglets and was highest in the caudal segments of the small intestine (P < 0.001). These data suggest that creep feeding could be a useful tool in the prevention of post-weaning diarrhoea.     

Alterations in piglet small intestinal structure at weaning

The small intestinal mucosa of 112 piglets aged between 21 and 32 days was examined to identify the effects on its structure of weaning and of consumption of creep food. In unweaned control pigs a gradual increase in crypt depth occurred with age, while villus height altered little. In contrast, weaned pigs showed a highly significant increase in crypt depth and an increase in the complexity of villus morphology with a dramatic reduction in villus height. Crypts elongated most in the distal small intestine, while the loss of villus height was greatest proximally. No inflammatory reaction was seen and the alterations were not influenced by consumption of creep food before weaning. This failed to support the hypothesis that hypersensitivity to dietary antigens is involved in the aetiology of such intestinal changes. The reduction in small intestinal absorptive area and the appearance of a less mature enterocyte population help to explain the increased susceptibility of the pig to diarrhoea and growth checks in the post-weaning period.     

Effect of rearing environment and age on gut development of piglets at weaning

Outdoor reared pigs are reported to be larger at weaning than indoor reared pigs and respond better to the weaning process. This may be due to enhanced gut development associated with increased size. Eighty sows were allocated to either indoor or outdoor farrowing on the basis of size, parity and past performance. Resulting litters were weaned at either 4 or 6 weeks of age. On days 26 and 40 of age, 40 (10/treatment) and 20 piglets (10/treatment still unweaned) were killed to measure intestinal morphology. Data were analysed as a 2 × 2 factorial using the GLM procedures of Minitab 12.2. Pigs reared outdoors were larger than those reared indoors at both weaning ages, pigs weaned at 6 weeks were heavier than those weaned at 4 weeks, 8.4 versus 7.4 kg at 4 weeks and 12.9 versus 10.5 kg at 6 weeks respectively (± 0.25, P ≤ 0.001). There were no differences in small intestine size relative to body weight due to rearing environment and no differences in gut morphology. When corrected for body weight, 6 week pigs had heavier small intestines than 4 week pigs, 0.39 (± 0.010) versus 0.34 (± 0.007) g/cm length, respectively (P ≤ 0.001). Six week unweaned pigs had similar villus heights to 4 week unweaned pigs but wider villi (P < 0.05) and deeper crypts, for example, at the 25% site crypt depths were 236 and 193 μm (± 7.7/5.5) respectively (P < 0.001). Hence increased piglet size due to outdoor rearing did not advance gut maturation whereas increased piglet size due to age did influence maturation of gut structure.     

Effects of immune-mediated enteroluminal neltrophil emigration on intestinal function in pigs.

Intestinal function was assessed in cannulated loops of porcine proximal jejunum during immune-mediated emigration of neutrophils into the intestine. Net water, net sodium, net chloride, undirectional sodium and unidirectional chloride fluxes were measured before and after intestinal exposure to an antigen in both sensitized and nonsensitized pigs. Neutrophil emigration was assessed histologically. The results indicate that fluid and electrolyte movements in the intestine are not significantly altered during immune-mediated enteroluminal neutrophil emigration suggesting that the neutrophil response does not interfere with intestinal function.     

Influence of creep feeding and weaning on brush border enzyme activities in the piglet small intestine

The activities of the enterocyte brush border enzymes lactase (beta-D galactoside galactohydrolase, EC 3.2.1.23) and sucrase (sucrose alpha-D glucohydrolase, EC 3.2.1.48) were measured at set percentage lengths along the small intestines of 112 piglets killed between 21 and 32 days of age. The influences on these activities of consumption of creep feed and of weaning were recorded. Weaning at three weeks old resulted in large, rapid reductions in lactase activity at most sites along the small intestine; sucrase activity declined temporarily and then recovered. Minimum values were recorded about four to five days after weaning. Similar changes were observed whether or not creep feed was consumed before weaning. Continued consumption of creep feed by unweaned pigs over the 21 to 32 day period also produced small but significant reductions in lactase activities. The large loss of digestive enzyme activities at brush borders in weaned animals coincided with a reduced ability to absorb xylose and to checks in growth rate in otherwise healthy piglets.     

Effect of creep feeding on structural and functional changes of the gut of early weaned pigs

Dose-dependent hypersensitivity responses mounted against antigenic constituents of creep feeds have been previously implicated in intestinal damage, digestive disorders and impaired performance of early weaned pigs. In the present study biochemical and histological investigations of the small intestine were undertaken to determine the putative relationship between creep feed level and hypersensitivity response in pigs weaned at 14 days. Creep feed was administered by gastric intubation and weaned pigs received the same diet by gastric intubation for five days. Mucosal structure and function at weaning were not affected by creep feeding regimen. Villus height decreased and crypt depth increased in weaned compared to suckled pigs, but morphology was unaffected by prior exposure to creep. Xylose absorption was not influenced by either creep feed level or weaning. Intraepithelial lymphocyte numbers increased during weaning but were not affected by the creep feeding regimen. Mucosal carbohydrase activity in weaned pigs was not significantly affected by preweaning treatment. The results do not support the hypothesis that post weaning changes in structure and function of the gut are related to creep feed level or to immune responses to dietary antigens.     

Effects of weaning and syndyphalin-33 on expression of melanocortinergic appetite-regulating genes in swine

Syndyphalin-33 (SD-33) increases feed intake in sheep and recently weaned pigs. To assess the effects of SD-33 on hypothalamic gene expression, hypothalami were collected from unweaned pigs (n=19; 21±3 d of age) on day 0. Remaining pigs received an intramuscular injection of 0.5 μmole/kg SD-33 (SD) or saline (VEH) and weaned into individual pens. On days 1, 4, and 7 after weaning, hypothalami were collected from subsets of pigs (n=8 or 9) within each treatment group. Expression of μ-opioid receptor (MOR) was less in SD pigs than in VEH pigs on day 1 and day 4, suggesting down-regulation of the receptor by SD-33. Expression of hypothalamic melanocortin 4 receptor (MC4R) at 1 d after weaning was increased in VEH pigs (but not SD pigs) relative to levels before weaning. Expression of AGRP was not significantly altered by weaning or treatment at 1 d after weaning. At 4 d after weaning, expression of AGRP was greater in SD pigs than in VEH pigs, but at day 7 expression was less in SD pigs than in VEH pigs. A strong positive correlation was noted between expression levels of MOR and MC4R across treatment and time. Treatment with SD-33 appeared to partially abrogate the effects of weaning on expression of two key appetite-regulating genes within 24 h. Effects of SD-33 appear to be mediated at least in part by the μ-opioid receptor and include actions on the melanocortinergic pathway.     

Effect of osmolality on net fluid absorption in non-infected and ETEC-infected piglet small intestinal segments

In the small intestinal segment perfusion model the effect of osmolality on net fluid absorption in enterotoxigenic Escherichia coli (ETEC)-infected and non-infected small intestinal segments of piglets was investigated. In ETEC-infected segments net fluid absorption was reduced. Lowering the osmolality from 375 to 150 mOsmol/l by reducing sodium chloride concentrations increased net fluid absorption. There was a linear relationship between osmolality and net fluid absorption for both non-infected and ETEC-infected segments. Below 150 mOsmol/l the inverse relationship between osmolality and net fluid absorption disappeared. Substitution of sodium chloride with mannitol decreased net fluid absorption since mannitol cannot be actively absorbed. In ETEC-infected segments perfused with oral rehydration solution net fluid absorption significantly increased compared to a sodium chloride solution of similar osmolality, probably because of the high glucose concentration. Supplying hypotonic sodium chloride fluids to piglets can be beneficial in replenishing water and electrolyte losses in case of infectious diarrhoea.     

断奶应激对仔猪肠黏膜形态的影响

在仔猪断奶过渡期，胃肠结构受损是很普遍的，断奶后一段时间内，胃肠结构受损程度不同，本文研究了断奶后7d内（断奶后0-6d)，仔猪小肠黏膜形态的变化，试验仔猪28日龄断奶。试验分7组，每组6头仔猪。从断奶当天开始，每1d定时定点剖杀取小肠前段，小肠中部，小肠后段作组织切片，观察其绒毛高度，隐窝深度。结果表明，断奶后前4d，绒毛高度缩短，隐窝加深，断奶后第4d绒毛高度最短，断奶后第5d开始恢复。     

The osmolality of caecal contents in piglets following weaning

Pigs weaned for five days had caecal contents with significantly lower osmolalities than those of unweaned animals of the same age. Supplementation of a standard weaning diet with therapeutic levels of oxytetracycline to suppress the normal large intestinal microbial flora did not significantly further reduce osmolarity of caecal contents after weaning. This observation suggests that microbial activity in the large intestine may not be sufficiently developed by five days after weaning to have a major influence on absorptive processes at that site. Incomplete development of the large intestinal microflora may be one more factor which acts to predispose the young pig to diarrhoea after weaning.     

Small intestinal morphology and disaccharidase activities in early-weaned piglets fed a diet containing spray-dried porcine plasma

The purpose of this study was to test whether dietary spray-dried porcine plasma (SDPP) in early-weaned piglets prevents small intestinal villus atrophy by trophic or protective activity. Fifty-four weaned, 18-day-old piglets were used to determine the effect of dietary SDPP on small intestinal villus length, crypt depth, enterocyt mitotic activity and brush border enzyme activities during the first week after weaning. The piglets were offered a diet containing either 8% SDPP or 8% casein. At 2 and 7 days after weaning, piglets were anaesthetized to provide samples of the small intestinal wall and killed immediately afterwards. There were no differences in daily gain and daily feed intake between the two dietary treatments. At day 2 after weaning, all piglets showed a marked reduction in villus height when compared with baseline values. In all piglets, small intestinal enterocyte mitotic activity had decreased by day 2 and was increased again on day 7. There were no significant effects of dietary SDPP on small intestinal villus length, crypt depth and enterocyt mitotic activity. This indicates that SDPP has no trophic effect on the small intestinal mucosa and that it does not protect against the damaging effect on the small intestinal villi that is associated with the process of weaning. There was no effect of SDPP on lactase-, sucrase- or maltase-specific activities that are a measure of the digestive function of the small intestine. It can be concluded that SDPP versus casein has no effect on small intestinal morphology and disaccharidase activities in early weaned piglets kept under low infection pressure.     

Influence of weaning age on the villous height and disaccharidase activities in the porcine small intestine

Body weight gain after weaning is correlated with villous height and disaccharidase activity. This evidence suggests that the maintenance of the small intestinal structure and function after weaning is important for the growth of piglets. We demonstrated that the influence of weaning age was obtained by disaccharidase activities and villous height in eight sections of the porcine small intestine. Therefore, we designed three weaning ages (weaned at the ages of 14, 21 or 28 days) and the piglets were slaughtered after 7 or 14 days post‐weaning. The remaining suckling piglets were slaughtered at the age of 1, 7, 14, 21 and 28 days. Four piglets were slaughtered at each event; therefore, 44 piglets were used in this study. Villous height and disaccharidase activities were measured in each section of the small intestine. Early weaning such as that at 14 days had severe influence on villous and disaccharidase activities. In particular, weaning of 14‐day‐olds did not result in maltase activity at least 2 weeks post‐weaning. Accordingly, the weaning age of crossbred piglets is recommended to be at least 21 days or more on the basis of villous height and disaccharidase activity analyses.     

Effects of weaning on diarrhea caused by enterotoxigenic Escherichia coli in three-week-old pigs

We attempted to determine whether weaning is required for induction of diarrhea in pigs with postweaning enterotoxigenic Escherichia coli infection. Three-week-old newly weaned pigs and their suckling littermates were inoculated with the K88+ enterotoxigenic E coli strain M1823B. Fourteen of 21 weaned and 12 of 20 suckling pigs were genetically resistant to intestinal adhesion by the K88+ strain of E coli; they remained healthy, and gained weight at similar rates. Both groups of K88-resistant pigs gained weight faster, and shed fewer bacteria of strain M1823B in their feces, than did their K88-susceptible counterparts. Diarrhea developed in K88-susceptible pigs in the weaned (6 of 7 pigs) and suckling (4 of 8 pigs) groups, and 1 of the 4 affected suckling pigs died from complications resulting from diarrhea. The incidences of diarrhea, weight gain rates, and the numbers of strain M1823B shed in feces of susceptible weaned and suckling pigs were not significantly (P greater than 0.05) different. Diarrhea scores of susceptible weaned pigs were significantly (P less than 0.02) higher than those of susceptible suckling pigs on the second day after inoculation. In this experimental model, it was concluded that weaning is not required for induction of diarrhea, but may modestly increase its severity.     

Effects of diet on acidic and neutral goblet cell populations in the small intestine of early weaned pigs.

Effects of dietary manipulation on Alcian blue-positive (AB+) and periodic acid-Schiff-positive (PAS+) goblet cell populations were determined for the villi and intestinal crypts in the small intestine of early weaned pigs. Pigs were weaned at 21 days of age and samples from the distal portions of the duodenum and the middle and distal portions of the jejunum were obtained when pigs were 21, 24, 27, 30, 33, and 36 days old. Pigs were assigned to 1 of 3 dietary treatments; all diets contained 20% protein, on the basis of hydrolyzed casein, soybean meal, or corn-soybean meal. By day 24, three days after weaning, the populations of AB+ and PAS+ goblet cells were markedly decreased, regardless of diet. Goblet cell populations in the villi tended to increase from 3 to 15 days after weaning, whereas those in the intestinal crypts remained low throughout the study. Differences between any of the dietary treatments were not apparent for AB+ or PAS+ goblet cell populations in the villi or in the intestinal crypts. It appeared that early weaning per se, and not diet, was the primary cause for decreases in goblet cell populations.     

The effects of weaning age, diet composition, and categorisation of creep feed intake by piglets on diarrhoea and performance after weaning

This study investigated the effects of weaning age, diet, and classification of piglets as ‘eaters’ or ‘non eaters’ of creep feed in lactation, on production and diarrhoea after weaning. Four antimicrobial-free diets were offered in lactation and for 14 days after weaning: (i) wheat–soy based diet with animal and vegetable (‘mixed’) protein sources (COMM), (ii) heat-processed rice (HPR) with barley hulls and potato starch and mixed protein sources (RBHPS), (iii) HPR with sugar-beet pulp and mixed protein sources (RSBP), and (iv) HPR with mixed protein sources (R). Piglets were individually examined for diarrhoea daily for 14 days after weaning, and antibiotic treatments were individually recorded. Faecal swabs were taken on day 10 after weaning and scored for β-haemolytic Escherichia coli. There were significant main effects of weaning age and diet (both P < 0.001) on daily gain between weaning and 14 days after weaning. Pigs weaned later grew 50 g/day more than pigs weaned earlier, and pigs fed the COMM diet grew slower than pigs fed the rice-based diets. The number of antibiotic treatments was influenced by diet (P < 0.001), with most treatments (2.1) given to pigs fed the diet RBHPS. Faecal score was influenced by a weaning age and diet interaction (P < 0.01). There was no correlation (P > 0.05) between the number of antibiotics treatments and the E. coli score.     

Incidence of rotavirus in artificially reared pigs and some effects of diarrhoea on the physiology and histology of the gastrointestinal tract

Pigs reared on a milk substitute from two days old often developed diarrhoea, but suckled littermates remained healthy. Only in a few pigs was diarrhoea associated with the presence of rotavirus. Rotavirus was also present in some healthy pigs, and was associated with a reduction in villus length. Pigs with diarrhoea usually had an increased amount of digesta in the stomach and a reduction in lactase activity in the small intestine but villus length was unchanged. There was no evidence of lactose malabsorption.     

Effects of age and diet on small intestinal structure and function in gnotobiotic piglets

The effects of age and dietary change on the structure and function of piglet small intestine were investigated in gnotobiotic pigs. The small intestinal mucosa was damaged when gnotobiotic pigs were weaned on to a pelleted meal diet; villus height, crypt cell production rate, and activities of brush border enzymes were reduced. Small intestinal damage was associated with reduced weight gain over a three week period; diarrhoea was not observed. The continuous consumption of meal appeared to perpetuate the intestinal damage for three weeks, although evidence of intestinal repair, as indicated by an increased crypt cell production rate, was present three weeks after weaning. Antibodies to soya antigen were detected in serum after weaning and the intestinal damage could have been caused by antibody-mediated immune reactions to soya proteins. Villi of milk fed gnotobiotic pigs shortened significantly with age.     

Immune responses of piglets to weaning stress: impacts of photoperiod

An acute stress response can be provoked by abrupt social, nutritional, and environmental changes associated with weaning, and this may disrupt homeostasis and thus compromise well-being. Manipulating environmental factors, such as photoperiod, might provide a simple way to reduce the physiological consequences that piglets experience due to weaning stress. The objective of this study was to evaluate the impacts of photoperiod manipulation across various weaning ages on leukocyte populations, lymphocyte proliferation, natural killer cytotoxicity (NK), chemotaxis, phagocytosis, and immunoglobulin G, cortisol, and BW of piglets during the nursery phase. Sixty-eight crossbred piglets were obtained from sows kept on a short-day (8 h of light/d) photoperiod from d 90 of gestation until weaning. Piglets were weaned at 14, 21, or 28 d of age and kept on a short or long (16 h of light/d) photoperiod until 10 wk of age. Piglet BW and blood samples were collected at weaning and at 6, 8, and 10 wk of age. Pigs weaned at 28 d had reduced neutrophil counts (P < 0.001), phagocytosis (P < 0.001), and lymphocyte proliferation (P < 0.05) at weaning compared with those weaned at 14 and 21 d. Pigs weaned at 21 d tended to have lower (P = 0.08) lymphocyte counts than did pigs weaned at 14 or 28 d. Pigs weaned at 14 d had reduced (P < 0.01) NK relative to those weaned at 21 or 28 d. Photoperiod also influenced pig BW and immune status. Generally, those pigs on the long-day photoperiod and weaned at 28 d were heavier (P < 0.001) than their counterparts weaned at 14 or 21 d. At 6 wk of age, NK was greater (P = 0.002) in pigs kept on a long day and weaned at 14 or 21 d than in pigs weaned at 28 d. Phagocytosis was less (P = 0.005) at 6 wk of age, but was greater at 8 wk, in piglets kept on the long day and weaned at 28 d than in long-day pigs weaned at 14 or 21 d. These results suggest that photoperiod differentially influences immune responses in piglets weaned at different ages and indicate an inverse relationship between growth and immune status. Here, weaning at 28 d and a long-day photoperiod was the treatment combination that was most physiologically beneficial to piglets, whereas a 14-d weaning and short-day photoperiod was least physiologically beneficial.     

Effects of dietary quillaja saponin and curcumin on the performance and immune status of weaned piglets

The objective of this study was to determine whether dietary quillaja saponin and curcumin (extract of turmeric) can modify piglet immune status and performance immediately after weaning. Piglets (n = 192) were weaned at 29 +/- 0.1 d and allocated to treatment (six replicates of eight pig per treatment) accounting for weight, litter, and gender, using a 2 x 2 factorial arrangement. Factors were diets with or without (as-fed basis) quillaja saponin (750 mg/kg during wk 1, 300 mg/kg during wk 2 to 3) and with or without dietary curcumin (200 mg/kg). Diets were fed ad libitum for 20 d after weaning. Feed intake was measured daily. Piglets were weighed at weaning, d 7, 14, and 20 after weaning. On each of d 6 and 20 after weaning, eight pigs per treatment were sacrificed for blood and tissue collection. Treatment had no effect on piglet growth. The ADFI and G:F were similar for all treatments between d 0 and 14 of the trial. Between d 15 and 20, ADFI and G:F were lower in quillaja-supplemented piglets (ADFI = 621 vs. 572 g/d; G:F = 0.75 vs. 0.85; P < 0.05). Serum immunoglobulin (Ig) G, IgA, interferon-gamma, and C-reactive protein (CRP) did not differ among treatments on d 6 after weaning. On d 20, IgG and CRP were greater (P < 0.05) in saponin-supplemented pigs (IgG = 17.5 vs. 11.4 mg/mL; CRP = 26.98 vs. 12.5 mg/mL). Small intestine villus and crypt measurements did not differ among treatments on either d 6 or 20. Saponin supplementation during the postweaning period seemed to potentiate an immune response in the weaned piglet but had a detrimental effect on the utilization of feed. Dietary curcumin had no influence on any measured aspect of pig performance or immune status.     

Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time.

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.